stripping lug bolts

[BTL-A4]

I've stripped at least 2, probably 5, of the 20 lug bolts on my four wheels. I'm not sure why. They are going in just fine. I start them by hand, then use an impact driver to drive them on the wheel. I tighten them to the proper torque (108 ft-lbs) with a torque wrench. I use anti-seize grease on the threads and the ball part. Some tighten just fine, a few others just spin.

What's weird is how they look when I pull them out. The first 1/4" or so is fine, they are stripped for the next 3/8", then they are fine. The part that is stripped is where they engage the wheel hub.

I ran a tap in the hole and it is fine. Looks fine, too. I can thread a bolt in there by hand just fine.

It as if they go on, then something strips them. I thought the wheel hub threads would be trashed, but they are not. Any ideas what is causing this?

 

[toolaholic]

How far on by hand . You should be able to spin them on a couple of turns. Just one or two turns and it could be cross threaded. An impact will easily strip those threads . I actually have a 1/2 drive thumbwheel to start lug nuts. I put spark plugs in with a thumb wheel. Hard to strip things with a low torque thumbwheel.

 

[u2slow]

Be careful with neverseize. Its a friction modifier, and results in overtorquing. (i.e. your tool may be set for 108# but effective torque could be 130# or more.)

Otherwise its just a matter of good threads in the hub, and the bolt. If in doubt, chase the threads with a tap/die. The stripped ones will need to be replaced, obviously.

 

[BTL-A4]

How far on by hand . You should be able to spin them on a couple of turns. Just one or two turns and it could be cross threaded. An impact will easily strip those threads . I actually have a 1/2 drive thumbwheel to start lug nuts. I put spark plugs in with a thumb wheel. Hard to strip things with a low torque thumbwheel.

That's what I thought, and that may be the case for some of these, but how the heck did the first part of the bolt in the picture go in fine, then the next part get stripped? Are lug bolts on the softer side?

 

[PCustoms]

108 ft/lbs....

What vehicle is this on?

 

[BTL-A4]

Be careful with neverseize. Its a friction modifier, and results in overtorquing. (i.e. your tool may be set for 108# but effective torque could be 130# or more.)

Otherwise its just a matter of good threads in the hub, and the bolt. If in doubt, chase the threads with a tap/die. The stripped ones will need to be replaced, obviously.

Good to know, thanks. I think I just need the grease on the ball part anyway.

I did chase the threads in the hub with a tap, and they are fine. I have some new bolts coming, but I wanted to find out what causes this so I don't do it again.

 

[BTL-A4]

108 ft/lbs....

What vehicle is this on?

A 1972 Porsche 914. Haynes Manual has 108 lb-ft. Maybe the grease on the threads is causing me to over-torque the bolts?

 

[The Cobbler]

lug nuts should go on dry, no lubricant.
the bolt thread doesn't look all that great but it may be just the picture.

 

[Bogie1632]

What kind of antiseize are you using? My handy dandy quick reference book shows antisieze coefficient changes with zinc is 0.75, nickle or graphite is 0.65, copper-graphite is 0.80. If your not adjusting your torque wrench your definitely going past the recommended 106 ft/lbs. Might be time to just do them dry or adjust for the change using your antiseize.

V/R
Bogie

 

[BTL-A4]

What kind of antiseize are you using? My handy dandy quick reference book shows antisieze coefficient changes with zinc is 0.75, nickle or graphite is 0.65, copper-graphite is 0.80. If your not adjusting your torque wrench your definitely going past the recommended 106 ft/lbs. Might be time to just do them dry or adjust for the change using your antiseize.

V/R
Bogie

Permatex #80078. It has Aluminum and Graphite in it.

I just looked it up and found this: "Not for use on wheel lug nut or stud applications".

Looks like that's the problem! The Permatex site didn't specify why it can't be used, though. I'm sure it's due to what has been suggested by other in this thread, though.

Edit: there is lubricated torque and un-lubricated torque. It's friction that holds the parts together.

 

[Keister]

check some other sources on that torque spec . that seems very high to start with. Lube makes it worse

 

[Bigblue&Goldie]

You've over torqued them and essentially stripped them where they go through the flange. Replace them all at this point. Put new ones in clean and free of lubricant/antiseize. Start by hand, finish with the torque wrench. Also, be careful torquing them down in case the threads in the hubs are trash too (even though you've checked them with a tap).

 

[The Cobbler]

... Also, be careful torquing them down in case the threads in the hubs are trash too (even though you've checked them with a tap).

A tap won't really identify threads that have the tops off, in my opinion. its not going to find low spots, just high spots.

 

[BTL-A4]

check some other sources on that torque spec . that seems very high to start with. Lube makes it worse

That spec comes from the Haynes Manual. For comparison, it's 140 ft-lbs for my Chevy Silverado.

However, on the 914 forum, some posters say 94 ft-lbs for alloy wheels, as does a chart on a Porsche parts site.

Thanks for the suggestion! I think I'll use the lower spec, since I have alloy wheels.

 

[BTL-A4]

You've over torqued them and essentially stripped them where they go through the flange. Replace them all at this point. Put new ones in clean and free of lubricant/antiseize. Start by hand, finish with the torque wrench. Also, be careful torquing them down in case the threads in the hubs are trash too (even though you've checked them with a tap).

Yeah, I think I'll do as much by hand as possible, then use the torque wrench and pull carefully. I can feel it just keep going instead of stopping at the proper torque. The good thing is the wheel hubs are part of the brake discs so I can replace them if they are trashed.

 

[Bigblue&Goldie]

A tap won't really identify threads that have the tops off, in my opinion. its not going to find low spots, just high spots.

I agree. Not ideal. I personally wouldn't have run a tap through. That's why I was saying to be careful because it's hard to say how compromised they are.

 

[BTL-A4]

I agree. Not ideal. I personally wouldn't have run a tap through. That's why I was saying to be careful because it's hard to say how compromised they are.

If I took a picture and posted it here could anyone tell? How else would I tell? By feel?

 

[Bigblue&Goldie]

Put a new lug bolt in and wiggle it around is about the only way I can think of. If it feels super loose, they might be done for. I'd skip the rattle gun and put them in by hand. If they take the torque spec without issue and maintain that torque, you will be fine.



This isn't your issue, but for those reading it might be helpful.....
With new or freshly painted/powdercoated wheels lugs nuts will often work loose until the coating has been worn away. For such wheels, tighten and loosen the lugs 4 or 5 times to get the coating worn down. Ideally, the lug seats wouldn't be painted/coated, but they often are.

 

[rsanter]

I suspect that hat the threads in the hub are damaged and you now have less contact area for the bolt threads to contact which leads to stripping the bolts.

I have those kind of lug bolts, I would do a stud conversion and use lug nuts

 

[Lassen Forge]

Why are you using anti sieze on lug nuts? Your 108# torque is for dry threads. Add grease - and you'll overtorque wihtout knowing it.

Regardless, my guess is you may need to replace your hubs... I've seen some people retap oversize and use larger lugbolts, but thats iffy...

Whatever happens, good luck!

 

[king nero]

Using anti-seize, or any type of lubricant, will easily change the coefficient of friction from 0.10 to 0.30, meaning a 200% increase or x3 the original value.

All of this is not very accurate, you could start at 0.15 and end up with 0.60, it's just to give an idea of the increase in clamping force between dry and lubed. Very easy to double, triple, quadruple the clamping force, especially if any lube gets on the interface between the conical part of the bolt and seating surface in the alloy wheel.

 

[danielbuck]

I would just not use anti-seize. I rarely used it on lugnuts that have a covered end on them. If they are open lug nuts where the threads stick out beyond the nut, I might consider using anti-seize then. my F250 calls for 160ftlbs of final torque with flat (hub centric) wheels.

I'd probably just go ahead and replace ALL of the wheel studs, and run new lug nuts. It's possible they were cheap, or somehow a bad batch that is softer than normal?


(edit) sorry, just looked at that photo again, you have a different style mounting than what I'm used to.